Delivery of alprazolam, estazolam, midazolam or triazolam through an inhalation route

ABSTRACT

The present invention relates to the delivery of alprazolam, estazolam, midazolam or triazolam through an inhalation route. Specifically, it relates to aerosols containing alprazolam, estazolam, midazolam or triazolam that are used in inhalation therapy. In a composition aspect of the present invention, the aerosol comprises particles comprising at least 5 percent by weight of alprazolam, estazolam, midazolam or triazolam. In a method aspect of the present invention, alprazolam, estazolam, midazolam or triazolam is delivered to a mammal through an inhalation route. The method comprises: a) heating a composition, wherein the composition comprises at least 5 percent by weight of alprazolam, estazolam, midazolam or triazolam, to form a vapor; and, b) allowing the vapor to cool, thereby forming a condensation aerosol comprising particles, which is inhaled by the mammal. In a kit aspect of the present invention, a kit for delivering alprazolam, estazolam, midazolam or triazolam through an inhalation route to a mammal is provided which comprises: a) a composition comprising at least 5 percent by weight of alprazolam, estazolam, midazolam or triazolam; and, b) a device that forms an alprazolam, estazolam, midazolam or triazolam containing aerosol from the composition, for inhalation by the mammal.

This application claims priority to U.S. provisional application SerialNo. 60/294,203 entitled “Thermal Vapor Delivery of Drugs,” filed May 24,2001, Rabinowitz and Zaffaroni, the entire disclosure of which is herebyincorporated by reference. This application further claims priority toU.S. provisional application Serial No. 60/317,479 entitled “AerosolDrug Delivery,” filed Sep. 5, 2001, Rabinowitz and Zaffaroni, the entiredisclosure of which is hereby incorporated by reference. Thisapplication further claims priority to U.S. provisional applicationSerial No. 60/345,876 entitled “Delivery of Alprazolam, Estazolam,Midazolam, and Triazolam Through an Inhalation Route,” filed Nov. 9,2001, Rabinowitz and Hale, the entire disclosure of which is herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to the delivery of alprazolam, estazolam,midazolam or triazolam through an inhalation route. Specifically, itrelates to aerosols containing alprazolam, estazolam, midazolam ortriazolam that are used in inhalation therapy.

BACKGROUND OF THE INVENTION

There are a number of compositions currently marketed for the treatmentof anxiety or insomnia. The compositions contain at least one activeingredient that provides for observed therapeutic effects. Among theactive ingredients in such compositions are alprazolam, estazolam,midazolam, and triazolam.

It is desirable to provide a new route of administration for alprazolam,estazolam, midazolam, and triazolam that rapidly produces peak plasmaconcentrations of the compound. The provision of such a route is anobject of the present invention.

SUMMARY OF THE INVENTION

The present invention relates to the delivery of alprazolam, estazolam,midazolam or triazolam through an inhalation route. Specifically, itrelates to aerosols containing alprazolam, estazolam, midazolam ortriazolam that are used in inhalation therapy.

In a composition aspect of the present invention, the aerosol comprisesparticles comprising at least 5 percent by weight of alprazolam,estazolam, midazolam or triazolam. Preferably, the particles comprise atleast 10 percent by weight of alprazolam, estazolam, midazolam ortriazolam. More preferably, the particles comprise at least 20 percent,30 percent, 40 percent, 50 percent, 60 percent, 70 percent, 80 percent,90 percent, 95 percent, 97 percent, 99 percent, 99.5 percent or 99.97percent by weight of alprazolam, estazolam, midazolam or triazolam.

Typically, the aerosol has a mass of at least 1 μg. Preferably, theaerosol has a mass of at least 10 μg. More preferably, the aerosol has amass of at least 20 μg.

Typically, the aerosol particles comprise less than 10 percent by weightof alprazolam, estazolam, midazolam or triazolam degradation products.Preferably, the particles comprise less than 5 percent by weight ofalprazolam, estazolam, midazolam or triazolam degradation products. Morepreferably, the particles comprise less than 2.5, 1, 0.5, 0.1 or 0.03percent by weight of alprazolam, estazolam, midazolam or triazolamdegradation products.

Typically, the aerosol particles comprise less than 90 percent by weightof water. Preferably, the particles comprise less than 80 percent byweight of water. More preferably, the particles comprise less than 70percent, 60 percent, 50 percent, 40 percent, 30 percent, 20 percent, 10percent, or 5 percent by weight of water.

Typically, at least 50 percent by weight of the aerosol is amorphous inform, wherein crystalline forms make up less than 50 percent by weightof the total aerosol weight, regardless of the nature of individualparticles. Preferably, at least 75 percent by weight of the aerosol isamorphous in form. More preferably, at least 90 percent by weight of theaerosol is amorphous in form.

Typically, the aerosol has an inhalable aerosol drug mass density ofbetween 0.02 mg/L and 10 mg/L. Preferably, the aerosol has an inhalableaerosol drug mass density of between 0.05 mg/L and 5 mg/L. Morepreferably, the aerosol has an inhalable aerosol drug mass density ofbetween 0.1 mg/L and 2 mg/L.

Typically, the aerosol has an inhalable aerosol particle density greaterthan 10⁶ particles/mL. Preferably, the aerosol has an inhalable aerosolparticle density greater than 10⁷ particles/mL. More preferably, theaerosol has an inhalable aerosol particle density greater than 10⁸particles/mL.

Typically, the aerosol particles have a mass median aerodynamic diameterof less than 5 microns. Preferably, the particles have a mass medianaerodynamic diameter of less than 3 microns. More preferably, theparticles have a mass median aerodynamic diameter of less than 2 or 1micron(s).

Typically, the geometric standard deviation around the mass medianaerodynamic diameter of the aerosol particles is less than 3.0.Preferably, the geometric standard deviation is less than 2.5. Morepreferably, the geometric standard deviation is less than 2.1.

Typically, the aerosol is formed by heating a composition containingalprazolam, estazolam, midazolam or triazolam to form a vapor andsubsequently allowing the vapor to condense into an aerosol.

In a method aspect of the present invention, either alprazolam,estazolam, midazolam or triazolam is delivered to a mammal through aninhalation route. The method comprises: a) heating a composition,wherein the composition comprises at least 5 percent by weight ofalprazolam, estazolam, midazolam or triazolam; and, b) allowing thevapor to cool, thereby forming a condensation aerosol comprisingparticles, which is inhaled by the mammal. Preferably, the compositionthat is heated comprises at least 10 percent by weight of alprazolam,estazolam, midazolam or triazolam. More preferably, the compositioncomprises 20 percent, 30 percent, 40 percent, 50 percent, 60 percent, 70percent, 80 percent, 90 percent, 95 percent, 97 percent, 99 percent,99.5 percent, 99.9 percent or 99.97 percent by weight of alprazolam,estazolam, midazolam or triazolam.

Typically, the delivered aerosol particles comprise at least 5 percentby weight of alprazolam, estazolam, midazolam or triazolam. Preferably,the particles comprise at least 10 percent by weight of alprazolam,estazolam, midazolam or triazolam. More preferably, the particlescomprise at least 20 percent, 30 percent, 40 percent, 50 percent, 60percent, 70 percent, 80 percent, 90 percent, 95 percent, 97 percent, 99percent, 99.5 percent, 99.9 percent or 99.97 percent by weight ofalprazolam, estazolam, midazolam or triazolam.

Typically, the aerosol has a mass of at least 1 μg. Preferably, theaerosol has a mass of at least 10 μg. More preferably, the aerosol has amass of at least 20 μg.

Typically, the delivered aerosol particles comprise less than 10 percentby weight of alprazolam, estazolam, midazolam or triazolam degradationproducts. Preferably, the particles comprise less than 5 percent byweight of alprazolam, estazolam, midazolam or triazolam degradationproducts. More preferably, the particles comprise less than 2.5, 1, 0.5,0.1 or 0.03 percent by weight of alprazolam, estazolam, midazolam ortriazolam degradation products.

Typically, the aerosol particles comprise less than 90 percent by weightof water. Preferably, the particles comprise less than 80 percent byweight of water. More preferably, the particles comprise less than 70percent, 60 percent, 50 percent, 40 percent, 30 percent, 20 percent, 10percent, or 5 percent by weight of water.

Typically, at least 50 percent by weight of the aerosol is amorphous inform, wherein crystalline forms make up less than 50 percent by weightof the total aerosol weight, regardless of the nature of individualparticles. Preferably, at least 75 percent by weight of the aerosol isamorphous in form. More preferably, at least 90 percent by weight of theaerosol is amorphous in form.

Typically, the particles of the delivered condensation aerosol have amass median aerodynamic diameter of less than 5 microns. Preferably, theparticles have a mass median aerodynamic diameter of less than 3microns. More preferably, the particles have a mass median aerodynamicdiameter of less than 2 or 1 micron(s).

Typically, the geometric standard deviation around the mass medianaerodynamic diameter of the aerosol particles is less than 3.0.Preferably, the geometric standard deviation is less than 2.5. Morepreferably, the geometric standard deviation is less than 2.1.

Typically, the delivered aerosol has an inhalable aerosol drug massdensity of between 0.02 mg/L and 10 mg/L. Preferably, the aerosol has aninhalable aerosol drug mass density of between 0.05 mg/L and 5 mg/L.More preferably, the aerosol has an inhalable aerosol drug mass densityof between 0.1 mg/L and 2 mg/L.

Typically, the delivered aerosol has an inhalable aerosol particledensity greater than 10⁶ particles/mL. Preferably, the aerosol has aninhalable aerosol particle density greater than 10⁷ particles/mL. Morepreferably, the aerosol has an inhalable aerosol particle densitygreater than 10⁸ particles/mL.

Typically, the rate of inhalable aerosol particle formation of thedelivered condensation aerosol is greater than 10⁸ particles per second.Preferably, the aerosol is formed at a rate greater than 10⁹ inhalableparticles per second. More preferably, the aerosol is formed at a rategreater than 10¹⁰ inhalable particles per second.

Typically, the delivered aerosol is formed at a rate greater than 0.1mg/second. Preferably, the aerosol is formed at a rate greater than 0.25mg/second. More preferably, the aerosol is formed at a rate greater than0.5, 1 or 2 mg/second.

Typically, where the condensation aerosol comprises alprazolam, between0.05 mg and 4 mg of alprazolam are delivered to the mammal in a singleinspiration. Preferably, between 0.1 mg and 2 mg of alprazolam aredelivered to the mammal in a single inspiration. More preferably,between 0.2 mg and 1 mg of alprazolam are delivered to the mammal in asingle inspiration.

Typically, where the condensation aerosol comprises estazolam, between0.05 mg and 4 mg of estazolam are delivered to the mammal in a singleinspiration. Preferably, between 0.1 mg and 2 mg of estazolam aredelivered to the mammal in a single inspiration. More preferably,between 0.2 mg and 1 mg of estazolam are delivered to the mammal in asingle inspiration.

Typically, where the condensation aerosol comprises midazolam, between0.05 mg and 4 mg of midazolam are delivered to the mammal in a singleinspiration. Preferably, between 0.1 mg and 2 mg of midazolam aredelivered to the mammal in a single inspiration. More preferably,between 0.2 mg and 1 mg of midazolam are delivered in a singleinspiration.

Typically, where the condensation aerosol comprises triazolam, between0.006 mg and 0.5 mg of triazolam are delivered to the mammal in a singleinspiration. Preferably, between 0.0125 mg and 0.25 mg of triazolam aredelivered to the mammal in a single inspiration. More preferably,between 0.025 mg and 0.125 mg of triazolam are delivered to the mammalin a single inspiration.

Typically, the delivered condensation aerosol results in a peak plasmaconcentration of alprazolam, estazolam, midazolam or triazolam in themammal in less than 1 h. Preferably, the peak plasma concentration isreached in less than 0.5 h. More preferably, the peak plasmaconcentration is reached in less than 0.2, 0.1, 0.05, 0.02, 0.01, or0.005 h (arterial measurement).

In a kit aspect of the present invention, a kit for deliveringalprazolam, estazolam, midazolam or triazolam through an inhalationroute to a mammal is provided which comprises: a) a compositioncomprising at least 5 percent by weight of alprazolam, estazolam,midazolam or triazolam; and, b) a device that forms an alprazolam,estazolam, midazolam or triazolam containing aerosol from thecomposition, for inhalation by the mammal. Preferably, the compositioncomprises at least 10 percent by weight of alprazolam, estazolam,midazolam or triazolam. More preferably, the composition comprises atleast 20 percent, 30 percent, 40 percent, 50 percent, 60 percent, 70percent, 80 percent, 90 percent, 95 percent, 97 percent, 99 percent,99.5 percent, 99.9 percent or 99.97 percent by weight of alprazolam,estazolam, midazolam or triazolam.

Typically, the device contained in the kit comprises: a) an element forheating the alprazolam, estazolam, midazolam or triazolam composition toform a vapor; b) an element allowing the vapor to cool to form anaerosol; and, c) an element permitting the mammal to inhale the aerosol.

BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 shows a device used to deliver alprazolam, estazolam, midazolamor triazolam containing aerosols to a mammal through an inhalationroute.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

“Aerodynamic diameter” of a given particle refers to the diameter of aspherical droplet with a density of 1 g/mL (the density of water) thathas the same settling velocity as the given particle.

“Aerosol” refers to a suspension of solid or liquid particles in a gas.

“Aerosol drug mass density” refers to the mass of alprazolam, estazolam,midazolam or triazolam per unit volume of aerosol.

“Aerosol mass density” refers to the mass of particulate matter per unitvolume of aerosol.

“Aerosol particle density” refers to the number of particles per unitvolume of aerosol.

“Alprazolam” refers to 8-chloro-1-methyl-6-phenyl-4H-s-triazolo-[4,3-α][1,4]benzodiazepine, which has an empirical formula of C₁₇H₁₃ClN₄.

“Alprazolam degradation product” refers to a compound resulting from achemical modification of alprazolam. The modification, for example, canbe the result of a thermally or photochemically induced reaction. Suchreactions include, without limitation, oxidation (e.g., of the methyl ormethylene unit) and hydrolysis (e.g., of the imine portion).

“Amorphous particle” refers to a particle that does not contain morethan 50 percent by weight of a crystalline form. Preferably, theparticle does not contain more than 25 percent by weight of acrystalline form. More preferably, the particle does not contain morethan 10 percent by weight of a crystalline form.

“Condensation aerosol” refers to an aerosol formed by vaporization of asubstance followed by condensation of the substance into an aerosol.

“Estazolam” refers to 8-chloro-6-phenyl-4H-s-triazolo[4,3-α][1,4]benzodiazepine, which has an empirical formula of C₁₆H₁₁ClN₄.

“Estazolam degradation product” refers to a compound resulting from achemical modification of estazolam. The modification, for example, canbe the result of a thermally or photochemically induced reaction. Suchreactions include, without limitation, oxidation (e.g., of the methyleneunit) and hydrolysis (e.g., of the imine portion).

“Inhalable aerosol drug mass density” refers to the aerosol drug massdensity produced by an inhalation device and delivered into a typicalpatient tidal volume.

“Inhalable aerosol mass density” refers to the aerosol mass densityproduced by an inhalation device and delivered into a typical patienttidal volume.

“Inhalable aerosol particle density” refers to the aerosol particledensity of particles of size between 100 nm and 5 microns produced by aninhalation device and delivered into a typical patient tidal volume.

“Mass median aerodynamic diameter” or “MMAD” of an aerosol refers to theaerodynamic diameter for which half the particulate mass of the aerosolis contributed by particles with an aerodynamic diameter larger than theMMAD and half by particles with an aerodynamic diameter smaller than theMMAD.

“Midazolam” refers to8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-α][1,4]benzodiazepine,which has an empirical formula of C₁₈H₁₃ClFN₃.

“Midazolam degradation product” refers to a compound resulting from achemical modification of midazolam. The modification, for example, canbe the result of a thermally or photochemically induced reaction. Suchreactions include, without limitation, oxidation (e.g., of the methyl ormethylene unit) and hydrolysis (e.g., of the imine portion).

“Rate of aerosol formation” refers to the mass of aerosolizedparticulate matter produced by an inhalation device per unit time.

“Rate of inhalable aerosol particle formation” refers to the number ofparticles of size between 100 nm and 5 microns produced by an inhalationdevice per unit time.

“Rate of drug aerosol formation” refers to the mass of aerosolizedalprazolam, estazolam, midazolam or triazolam produced by an inhalationdevice per unit time.

“Settling velocity” refers to the terminal velocity of an aerosolparticle undergoing gravitational settling in air.

“Triazolam” refers to8-chloro-6-(-o-chlorophenyl)-1-methyl-4H-s-triazolo-[4,3-α][1,4]benzodiazepine, which has an empirical formula of C₁₇H₁₂Cl₂N₄.

“Triazolam degradation product” refers to a compound resulting from achemical modification of triazolam. The modification, for example, canbe the result of a thermally or photochemically induced reaction. Suchreactions include, without limitation, oxidation (e.g., of the methyl ormethylene unit) and hydrolysis (e.g., of the imine portion).

“Typical patient tidal volume” refers to 1 L for an adult patient and 15mL/kg for a pediatric patient.

“Vapor” refers to a gas, and “vapor phase” refers to a gas phase. Theterm “thermal vapor” refers to a vapor phase, aerosol, or mixture ofaerosol-vapor phases, formed preferably by heating.

Formation of Alprazolam, Estazolam, Midazolam or Triazolam ContainingAerosols

Any suitable method is used to form the aerosols of the presentinvention. A preferred method, however, involves heating a compositioncomprising alprazolam, estazolam, midazolam or triazolam to produce avapor, followed by cooling of the vapor such that it condenses toprovide an alprazolam, estazolam, midazolam or triazolam comprisingaerosol (condensation aerosol). The composition is heated in one of twoforms: as pure active compound (i.e., pure alprazolam, estazolam,midazolam or triazolam); or, as a mixture of active compound and apharmaceutically acceptable excipient. Typically, the composition isheated on a solid support.

Pharmaceutically acceptable excipients are either volatile ornonvolatile. Volatile excipients, when heated, are concurrentlyvolatilized, aerosolized and inhaled with alprazolam, estazolam,midazolam or triazolam. Classes of such excipients are known in the artand include, without limitation, gaseous, supercritical fluid, liquidand solid solvents. The following is a list of exemplary carriers withinthe classes: water; terpenes, such as menthol; alcohols, such asethanol, propylene glycol, glycerol and other similar alcohols;dimethylformamide; dimethylacetamide; wax; supercritical carbon dioxide;dry ice; and mixtures thereof.

Solid supports on which the composition is heated are of a variety ofshapes. Examples of such shapes include, without limitation, cylindersof less than 1.0 mm in diameter, boxes of less than 1.0 mm thickness andvirtually any shape permeated by small (e.g., less than 1.0 mm-sized)pores. Preferably, solid supports provide a large surface to volumeratio (e.g., greater than 100 per meter) and a large surface to massratio (e.g., greater than 1 cm² per gram).

A solid support of one shape can also be transformed into another shapewith different properties. For example, a box of 0.25 mm thickness has asurface to volume ratio of approximately 8,000 per meter. Rolling thebox into a hollow cylinder of 1 cm diameter produces a support thatretains the high surface to mass ratio of the original box but has alower surface to volume ratio (about 400 per meter).

A number of different materials are used to construct the solidsupports. Classes of such materials include, without limitation, metals,inorganic materials, carbonaceous materials and polymers. The followingare examples of the material classes: aluminum, silver, gold, stainlesssteel, copper and tungsten; silica, glass, silicon and alumina;graphite, porous carbons, carbon yarns and carbon felts;polytetrafluoroethylene and polyethylene glycol. Combinations ofmaterials and coated variants of materials are used as well.

Where aluminum is used as a solid support, aluminum foil is a suitablematerial. Examples of silica, alumina and silicon based materialsinclude amphorous silica S-5631 (Sigma, St. Louis, Mo.), BCR171 (analumina of defined surface area greater than 2 m²/g from Aldrich, St.Louis, Mo.) and a silicon wafer as used in the semiconductor industry.Carbon yams and felts are available from American Kynol, Inc., New York,N.Y. Chromatography resins such as octadecycl silane chemically bondedto porous silica are exemplary coated variants of silica.

The heating of the alprazolam, estazolam, midazolam or triazolamcompositions is performed using any suitable method. Examples of methodsby which heat can be generated include the following: passage of currentthrough an electrical resistance element; absorption of electromagneticradiation, such as microwave or laser light; and, exothermic chemicalreactions, such as exothermic solvation, hydration of pyrophoricmaterials and oxidation of combustible materials.

Delivery of Alprazolam, Estazolam, Midazolam or Triazolam ContainingAerosols

Alprazolam, estazolam, midazolam and triazolam containing aerosols ofthe present invention are delivered to a mammal using an inhalationdevice. Where the aerosol is a condensation aerosol, the device has atleast three elements: an element for heating an alprazolam, estazolam,midazolam or triazolam containing composition to form a vapor; anelement allowing the vapor to cool, thereby providing a condensationaerosol; and, an element permitting the mammal to inhale the aerosol.Various suitable heating methods are described above. The element thatallows cooling is, in it simplest form, an inert passageway linking theheating means to the inhalation means. The element permitting inhalationis an aerosol exit portal that forms a connection between the coolingelement and the mammal's respiratory system.

One device used to deliver alprazolam, estazolam, midazolam or triazolamcontaining aerosol is described in reference to FIG. 1. Delivery device100 has a proximal end 102 and a distal end 104, a heating module 106, apower source 108, and a mouthpiece 110. An alprazolam, estazolam,midazolam or triazolam composition is deposited on a surface 112 ofheating module 106. Upon activation of a user activated switch 114,power source 108 initiates heating of heating module 106 (e.g, throughignition of combustible fuel or passage of current through a resistiveheating element). The alprazolam, estazolam, midazolam or triazolamcomposition volatilizes due to the heating of heating module 106 andcondenses to form a condensation aerosol prior to reaching themouthpiece 110 at the proximal end of the device 102. Air flow travelingfrom the device distal end 104 to the mouthpiece 110 carries thecondensation aerosol to the mouthpiece 110, where it is inhaled by themammal.

Devices, if desired, contain a variety of components to facilitate thedelivery of alprazolam, estazolam, midazolam or triazolam containingaerosols. For instance, the device may include any component known inthe art to control the timing of drug aerosolization relative toinhalation (e.g., breath-actuation), to provide feedback to patients onthe rate and/or volume of inhalation, to prevent excessive use (i.e.,“lock-out” feature), to prevent use by unauthorized individuals, and/orto record dosing histories.

Dosage of Alprazolam, Estazolam, Midazolam or Triazolam ContainingAerosols

For the short-term management of insomnia, estazolam is given orally atstrengths of 1 mg or 2 mg (PROSOM™ Tablets). Alprazolam is used for thetreatment of anxiety disorders and is provided for oral administrationat strengths of 0.25 mg, 0.5 mg, 1 mg or 2 mg (XANAX® Tablets).Midazolam is given (injection or syrup) either as an anesthetic oranxiolytic in a typical dose of 0.5 mg to 4 mg (VERSED®). Triazolam isused to treat insomnia as an oral formulation in strengths of 0.125 mgand 0.25 mg (HALCION® Tablets).

As aerosols, 0.05 mg to 4 mg of estazolam, 0.05 mg to 4 mg alprazolam,0.05 mg to 4 mg midazolam and 0.006 mg to 0.5 mg triazolam are generallyprovided per inspiration for the same indications. A typical dosage ofan alprazolam, estazolam, midazolam or triazolam aerosol is eitheradministered as a single inhalation or as a series of inhalations takenwithin an hour or less (dosage equals sum of inhaled amounts). Where thedrug is administered as a series of inhalations, a different amount maybe delivered in each inhalation. The dosage amount of alprazolam,estazolam, midazolam or triazolam in aerosol form is generally nogreater than twice the standard dose of the drug given orally or byinjection.

One can determine the appropriate dose of alprazolam, estazolam,midazolam or triazolam containing aerosols to treat a particularcondition using methods such as animal experiments and a dose-finding(Phase I/II) clinical trial. One animal experiment involves measuringplasma concentrations of an animal after its exposure to the aerosol.Mammals such as dogs or primates are typically used in such studies,since their respiratory systems are similar to that of a human. Initialdose levels for testing in humans are generally less than or equal tothe dose in the mammal model that resulted in plasma drug levelsassociated with a therapeutic effect in humans. Dose escalation inhumans is then performed, until either an optimal therapeutic responseis obtained or a dose-limiting toxicity is encountered.

Analysis of Alprozolam, Estazolam, Midazolam or Triazolam ContainingAerosols

Purity of an alprazolam, estazolam, midazolam or triazolam containingaerosol is determined using a number of methods, examples of which aredescribed in Sekine et al., Journal of Forensic Science 32:1271-1280(1987) and Martin et al., Journal of Analytic Toxicology 13:158-162(1989). One method involves forming the aerosol in a device throughwhich a gas flow (e.g., air flow) is maintained, generally at a ratebetween 0.4 and 60 L/min. The gas flow carries the aerosol into one ormore traps. After isolation from the trap, the aerosol is subjected toan analytical technique, such as gas or liquid chromatography, thatpermits a determination of composition purity.

A variety of different traps are used for aerosol collection. Thefollowing list contains examples of such traps: filters; glass wool;impingers; solvent traps, such as dry ice-cooled ethanol, methanol,acetone and dichloromethane traps at various pH values; syringes thatsample the aerosol; empty, low-pressure (e.g., vacuum) containers intowhich the aerosol is drawn; and, empty containers that fully surroundand enclose the aerosol generating device. Where a solid such as glasswool is used, it is typically extracted with a solvent such as ethanol.The solvent extract is subjected to analysis rather than the solid(i.e., glass wool) itself. Where a syringe or container is used, thecontainer is similarly extracted with a solvent.

The gas or liquid chromatograph discussed above contains a detectionsystem (i.e., detector). Such detection systems are well known in theart and include, for example, flame ionization, photon absorption andmass spectrometry detectors. An advantage of a mass spectrometrydetector is that it can be used to determine the structure ofalprazolam, estazolam, midazolam or triazolam degradation products.

Particle size distribution of an alprazolam, estazolam, midazolam ortriazolam containing aerosol is determined using any suitable method inthe art (e.g., cascade impaction). An Andersen Eight Stage Non-viableCascade Impactor (Andersen Instruments, Smyrna, Ga.) linked to a furnacetube by a mock throat (USP throat, Andersen Instruments, Smyrna, Ga.) isone system used for cascade impaction studies.

Inhalable aerosol mass density is determined, for example, by deliveringa drug-containing aerosol into a confined chamber via an inhalationdevice and measuring the mass collected in the chamber. Typically, theaerosol is drawn into the chamber by having a pressure gradient betweenthe device and the chamber, wherein the chamber is at lower pressurethan the device. The volume of the chamber should approximate the tidalvolume of an inhaling patient.

Inhalable aerosol drug mass density is determined, for example, bydelivering a drug-containing aerosol into a confined chamber via aninhalation device and measuring the amount of active drug compoundcollected in the chamber. Typically, the aerosol is drawn into thechamber by having a pressure gradient between the device and thechamber, wherein the chamber is at lower pressure than the device. Thevolume of the chamber should approximate the tidal volume of an inhalingpatient. The amount of active drug compound collected in the chamber isdetermined by extracting the chamber, conducting chromatographicanalysis of the extract and comparing the results of the chromatographicanalysis to those of a standard containing known amounts of drug.

Inhalable aerosol particle density is determined, for example, bydelivering aerosol phase drug into a confined chamber via an inhalationdevice and measuring the number of particles of given size collected inthe chamber. The number of particles of a given size may be directlymeasured based on the light-scattering properties of the particles.Alternatively, the number of particles of a given size may be determinedby measuring the mass of particles within the given size range andcalculating the number of particles based on the mass as follows: Totalnumber of particles−Sum (from size range 1 to size range N) of number ofparticles in each size range. Number of particles in a given sizerange=Mass in the size range/Mass of a typical particle in the sizerange. Mass of a typical particle in a given size range=π*D³*φ/6, whereD is a typical particle diameter in the size range (generally, the meanboundary of the MMADs defining the size range) in microns, φ is theparticle density (in g/mL) and mass is given in units of picograms(g⁻¹²).

Rate of inhalable aerosol particle formation is determined, for example,by delivering aerosol phase drug into a confined chamber via aninhalation device. The delivery is for a set period of time (e.g., 3 s),and the number of particles of a given size collected in the chamber isdetermined as outlined above. The rate of particle formation is equal tothe number of 100 nm to 5 micron particles collected divided by theduration of the collection time.

Rate of aerosol formation is determined, for example, by deliveringaerosol phase drug into a confined chamber via an inhalation device. Thedelivery is for a set period of time (e.g., 3 s), and the mass ofparticulate matter-collected is determined by weighing the confinedchamber before and after the delivery of the particulate matter. Therate of aerosol formation is equal to the increase in mass in thechamber divided by the duration of the collection time. Alternatively,where a change in mass of the delivery device or component thereof canonly occur through release of the aerosol phase particulate matter, themass of particulate matter may be equated with the mass lost from thedevice or component during the delivery of the aerosol. In this case,the rate of aerosol formation is equal to the decrease in mass of thedevice or component during the delivery event divided by the duration ofthe delivery event.

Rate of drug aerosol formation is determined, for example, by deliveringan alprazolam, estazolam, midazolam or triazolam containing aerosol intoa confined chamber via an inhalation device over a set period of time(e.g., 3 s). Where the aerosol is pure alprazolam, estazolam, midazolamor triazolam, the amount of drug collected in the chamber is measured asdescribed above. The rate of drug aerosol formation is equal to theamount of alprazolam, estazolam, midazolam or triazolam collected in thechamber divided by the duration of the collection time. Where thealprazolam, estazolam, midazolam or triazolam containing aerosolcomprises a pharmaceutically acceptable excipient, multiplying the rateof aerosol formation by the percentage of alprazolam, estazolam,midazolam or triazolam in the aerosol provides the rate of drug aerosolformation.

Utility of Alprazolam, Estazolam, Midazolam and Triazolam ContainingAerosols

Typical uses for alprazolam, estazolam, midazolam, andtriazolam-containing aerosols include without limitation the following:relief of the symptoms of situational anxiety, relief of acute panicattacks, relaxation of skeletal muscle, treatment of nausea andvomiting, induction of sleep, and sedation for medical or dentalprocedures. Alprazolam and estazolam containing-aerosols aredistinguished from midazolam and triazolam-containing aerosols primarilyby their durations of action, with alprazolam and estazolam havinghalf-lives of approximately 12 hours and midazolam and triazolam havinghalf-lives of approximately 3 hours. Thus triazolam ormidazolam-containing aerosols are typically used in instances where arapid offset of action is desired (e.g. in sedation for medical ordental procedures). In contrast, alprazolam or estazolam-containingaerosols are typically used in instances where a sustained action isdesired (e.g. in the case of a panic attack, where a rapid offset ofaction might predispose to another episode of panic).

The following examples are meant to illustrate, rather than limit, thepresent invention.

Alprazolam, estazolam and triazolam were purchased from Sigma(www.sigma-aldrich.com). Midazolam was obtained from Gyma Laboratoriesof America, Inc. (Westbury, N.Y.).

EXAMPLE 1 Volatilization of Alprazolam

A solution of 2.6 mg alprazolam in 120 μL dichloromethane was coated ona 3.6 cm×8 cm piece of aluminum foil. The dichloromethane was allowed toevaporate. Assuming a drug density of about 1 g/cc, the caluculatedthickness of the alprazolam coating on the 28.8 cm² aluminum solidsupport, after solvent evaporation is about, 0.9 microns. The coatedfoil was wrapped around a 300 watt halogen tube (Feit Electric Company,Pico Rivera, Calif.), which was inserted into a glass tube sealed at oneend with a rubber stopper. Running 75 V of alternating current (drivenby line power controlled by a variac) through the bulb for 6 s affordedalprazolam thermal vapor (including alprazolam aerosol), which collectedon the glass tube walls. Reverse-phase HPLC analysis with detection byabsorption of 225 nm light showed the collected material to be at least99.9% pure alprazolam. To obtain higher purity aerosols, one can coat alesser amount of drug, yielding a thinner film to heat. A lineardecrease in film thickness is associated with a linear decrease inimpurities.

EXAMPLE 2 Volatilization of Estazolam

A solution of 2.0 mg estazolam in 120 μL dichloromethane was coated on a3.6 cm×8 cm piece of aluminum foil. The dichloromethane was allowed toevaporate. Assuming a drug density of about 1 g/cc, the caluculatedthickness of the estazolam coating on the 28.8 cm² aluminum solidsupport, after solvent evaporation, is about 0.7 microns. The coatedfoil was wrapped around a 300 watt halogen tube (Feit Electric Company,Pico Rivera, Calif.), which was inserted into a glass tube sealed at oneend with a rubber stopper. Running 60 V of alternating current (drivenby line power controlled by a variac) through the bulb for 3 s, followedby 45 V for 11s, afforded estazolam thermal vapor (including estazolamaerosol), which collected on the glass tube walls. Reverse-phase HPLCanalysis with detection by absorption of 225 nm light showed thecollected material to be at least 99.9% pure estazolam.

EXAMPLE 3 Volatilization of Midazolam

A solution of 5.0 mg midazolam in 120 μL dichloromethane was coated on a3.6 cm×8 cm piece of aluminum foil. The dichloromethane was allowed toevaporate. Assuming a drug density of about 1 g/cc, the caluculatedthickness of the midazolamcoating on the 28.8 cm² aluminum solidsupport, after solvent evaporation, is about 1.7 microns. The coatedfoil was wrapped around a 300 watt halogen tube (Feit Electric Company,Pico Rivera, Calif.), which was inserted into a glass tube sealed at oneend with a rubber stopper. Running 60V of alternating current (driven byline power controlled by a variac) through the bulb for 6 s affordedmidazolam thermal vapor (including midazolam aerosol), which collectedon the glass tube walls. Reverse-phase HPLC analysis with detection byabsorption of 225 nm light showed the collected material to be at least99.9% pure midazolam.

EXAMPLE 4 Particle Size, Particle Density, and Rate of InhalableParticle Formation of Midazolam Aerosol

A solution of 17.1 mg midazolam in 200 μL dichloromethane was spread outin a thin layer on the central portion of a 4 cm×9 cm sheet of aluminumfoil. The dichloromethane was allowed to evaporate. Assuming a drugdensity of about 1 g/cc, the caluculated thickness of the midazolamcoating on the 28.8 cm² aluminum solid support, after solventevaporation, is about 4.8 microns. The aluminum foil was wrapped arounda 300 watt halogen tube, which was inserted into a T-shaped glass tube.One of the openings of the tube was sealed with a rubber stopper,another was loosely covered with the end of the halogen tube, and thethird was connected to a 1 liter, 3-neck glass flask. The glass flaskwas further connected to a large piston capable of drawing 1.1 liters ofair through the flask. Alternating current was run through the halogenbulb by application of 90 V using a variac connected to 110 V linepower. Within 1 s, an aerosol appeared and was drawn into the 1 L flaskby use of the piston, with collection of the aerosol terminated after 6s. The aerosol was analyzed by connecting the 1 L flask to aneight-stage Andersen non-viable cascade impactor. Results are shown intable 1. MMAD of the collected aerosol was 2.8 microns with a geometricstandard deviation of 1.9. Also shown in table 1 is the number ofparticles collected on the various stages of the cascade impactor, givenby the mass collected on the stage divided by the mass of a typicalparticle trapped on that stage. The mass of a single particle ofdiameter D is given by the volume of the particle, πD³/6, multiplied bythe density of the drug (taken to be 1 g/cm³). The inhalable aerosolparticle density is the sum of the numbers of particles collected onimpactor stages 3 to 8 divided by the collection volume of 1 L, givingan inhalable aerosol particle density of 5.5×10⁷ particles/mL. The rateof inhalable aerosol particle formation is the sum of the numbers ofparticles collected on impactor stages 3 through 8 divided by theformation time of 6 s, giving a rate of inhalable aerosol particleformation of 9.1×10⁹ particles/second.

TABLE 1 Determination of the characteristics of a midazolam condensationaerosol by cascade impaction using an Andersen 8-stage non-viablecascade impactor run at 1 cubic foot per minute air flow. Particle sizeAverage particle Mass Number of Stage range (microns) size (microns)collected (mg) particles 0 9.0-10.0 9.5 0.1 2.2 × 10⁵ 1 5.8-9.0 7.4 0.62.8 × 10⁶ 2 4.7-5.8 5.25 0.7 9.2 × 10⁶ 3 3.3-4.7 4.0 1.1 3.3 × 10⁷ 42.1-3.3 2.7 1.1 1.1 × 10⁸ 5 1.1-2.1 1.6 1.1 5.1 × 10⁸ 6 0.7-1.1 0.9 0.71.8 × 10⁹ 7 0.4-0.7 0.55 0.3 4.6 × 10⁹ 8   0-0.4 0.2 0.2 4.8 × 10¹⁰

EXAMPLE 5 Drug Mass Density and Rate of Drug Aerosol Formation ofMidazolam Aerosol

A solution of 16.7 mg midazolam in 200 μL dichloromethane was spread outin a thin layer on the central portion of a 4 cm×9 cm sheet of aluminumfoil. The dichloromethane was allowed to evaporate. Assuming a drugdensity of about 1 g/cc, the caluculated thickness of the midazolamcoating on the 36 cm² aluminum solid support, after solvent evaporation,is about 4.6 microns. The aluminum foil was wrapped around a 300 watthalogen tube, which was inserted into a T-shaped glass tube. One of theopenings of the tube was sealed with a rubber stopper, another wasloosely covered with the end of the halogen tube, and the third wasconnected to a 1 liter, 3-neck glass flask. The glass flask was furtherconnected to a large piston capable of drawing 1.1 liters of air throughthe flask. Alternating current was run through the halogen bulb byapplication of 90 V using a variac connected to 110 V line power. Withinseconds, an aerosol appeared and was drawn into the 1 L flask by use ofthe piston, with formation of the aerosol terminated after 6 s. Theaerosol was allowed to sediment onto the walls of the 1 L flask forapproximately 30 minutes. The flask was then extracted withdichloromethane and the extract analyzed by HPLC with detection by lightabsorption at 225 nm. Comparison with standards containing known amountsof midazolam revealed that 8.12 mg of >99% pure midazolam had beencollected in the flask, resulting in an aerosol drug mass density of8.12 mg/L. The aluminum foil upon which the midazolam had previouslybeen coated was weighed following the experiment. Of the 16.7 mgoriginally coated on the aluminum, all of the material was found to haveaerosolized in the 6 s time period, implying a rate of drug aerosolformation of 2.7 mg/s.

EXAMPLE 6 Volatilization of Triazolam

A solution of 2.0 mg triazolam in 120 μL dichloromethane was coated on a3.6 cm×8 cm piece of aluminum foil. The dichloromethane was allowed toevaporate. Assuming a drug density of about 1 g/cc, the caluculatedthickness of the triazolam coating on the 28.8 cm² aluminum solidsupport, after solvent evaporation, is about 0.7 microns. The coatedfoil was wrapped around a 300 watt halogen tube (Feit Electric Company,Pico Rivera, Calif.), which was inserted into a glass tube sealed at oneend with a rubber stopper. Running 75 V of alternating current (drivenby line power controlled by a variac) through the bulb for 2 s, followedby 45 V for 8 s, afforded triazolam thermal vapor (including triazolamaerosol), which collected on the glass tube walls. Reverse-phase HPLCanalysis with detection by absorption of 225 nm light showed thecollected material to be at least 99.85% pure triazolam.

EXAMPLE 7 Particle Size, Particle Density, and Rate of InhalableParticle Formation of Triazolam Aerosol

A solution of 16.4 mg triazolam in 200 μL dichloromethane was spread outin a thin layer on the central portion of a 4 cm×9 cm sheet of aluminumfoil. The dichloromethane was allowed to evaporate. Assuming a drugdensity of about 1 g/cc, the caluculated thickness of the triazolamcoating on the 36 cm² aluminum solid support, after solvent evaporation,is about 4.6 microns. The aluminum foil was wrapped around a 300 watthalogen tube, which was inserted into a T-shaped glass tube. One of theopenings of the tube was sealed with a rubber stopper, another wasloosely covered with the end of the halogen tube, and the third wasconnected to a 1 liter, 3-neck glass flask. The glass flask was furtherconnected to a large piston capable of drawing 1.1 liters of air throughthe flask. Alternating current was run through the halogen bulb byapplication of 90 V using a variac connected to 110 V line power. Within1 s, an aerosol appeared and was drawn into the 1 L flask by use of thepiston, with collection of the aerosol terminated after 6 s. The aerosolwas analyzed by connecting the 1 L flask to an eight-stage Andersennon-viable cascade impactor. Results are shown in table 1. MMAD of thecollected aerosol was 2.2 microns with a geometric standard deviation of2. Also shown in table 1 is the number of particles collected on thevarious stages of the cascade impactor, given by the mass collected onthe stage divided by the mass of a typical particle trapped on thatstage. The mass of a single particle of diameter D is given by thevolume of the particle, πD³/6, multiplied by the density of the drug(taken to be 1 g/cm³). The inhalable aerosol particle density is the sumof the numbers of particles collected on impactor stages 3 to 8 dividedby the collection volume of 1 L, giving an inhalable aerosol particledensity of 3.8×10⁶ particles/mL. The rate of inhalable aerosol particleformation is the sum of the numbers of particles collected on impactorstages 3 through 8 divided by the formation time of 6 s, giving a rateof inhalable aerosol particle formation of 6×10⁸ particles/second.

TABLE 1 Determination of the characteristics of a triazolam condensationaerosol by cascade impaction using an Andersen 8-stage non-viablecascade impactor run at 1 cubic foot per minute air flow. Particle sizeAverage particle Mass Number of Stage range (microns) size (microns)collected (mg) particles 0 9.0-10.0 9.5 0.0 0 1 5.8-9.0 7.4 0.3 1.4 ×10⁶ 2 4.7-5.8 5.25 0.3 4.0 × 10⁶ 3 3.3-4.7 4.0 0.7 2.1 × 10⁷ 4 2.1-3.32.7 1.2 1.2 × 10⁸ 5 1.1-2.1 1.6 1.5 7.0 × 10⁸ 6 0.7-1.1 0.9 0.7 1.8 ×10⁹ 7 0.4-0.7 0.55 0.1 1.2 × 10⁹ 8   0-0.4 0.2 0.0 0

EXAMPLE 8 Drug Mass Density and Rate of Drug Aerosol Formation ofTriazolam Aerosol

A solution of 0.6 mg triazolam in 200 μL dichloromethane was spread outin a thin layer on the central portion of a 4 cm×9 cm sheet of aluminumfoil. The dichloromethane was allowed to evaporate. Assuming a drugdensity of about 1 g/cc, the caluculated thickness of the triazolamcoating on the 28.8 cm² aluminum solid support, after solventevaporation, is about 0.2 microns. The aluminum foil was wrapped arounda 300 watt halogen tube, which was inserted into a T-shaped glass tube.One of the openings of the tube was sealed with a rubber stopper,another was loosely covered with the end of the halogen tube, and thethird was connected to a 1 liter, 3-neck glass flask. The glass flaskwas further connected to a large piston capable of drawing 1.1 liters ofair through the flask. Glass wool was placed in the tube connecting theflask to the piston._Alternating current was run through the halogenbulb by application of 90 V using a variac connected to 110 V linepower. Within seconds, an aerosol appeared and was drawn into the 1 Lflask by use of the piston, with formation of the aerosol terminatedafter 6 s. The aerosol was allowed to sediment onto the walls of the 1 Lflask for approximately 30 minutes. The flask and glass wool were thenextracted with dichloromethane and the extract analyzed by HPLC withdetection by light absorption at 225 nm. Comparison with standardscontaining known amounts of triazolam revealed that 0.17 mg of >99% puretriazolam had been collected in the flask, resulting in an aerosol drugmass density of 0.17 mg/L. The aluminum foil upon which the triazolamhad previously been coated was weighed following the experiment. Of the0.6 mg originally coated on the aluminum, all of the material was foundto have aerosolized in the 6 s time period, implying a rate of drugaerosol formation of 0.1 mg/s.

EXAMPLE 9 Delivery of Triazolam to a Dog

Apnea was induced in a dog, which was subsequently exposed to a 15 SLPMflow of air containing 140 μg of triazolam (condensation aerosol formedby volatilizing triazolam off of a heated, metal substrate; MMAD ˜1.1)through an endotracheal tube. This corresponded to approximately a 625cc volume of inhalation air delivered to the dog. Once the dog hadreceived the triazolam aerosol, an air supply valve was shut off for 5s, which simulated a 5 s breath hold. Following the hold, the dog wasallowed to exhale through an exhalation filter. Arterial blood sampleswere taken at the following intervals: 0 min, 0.25 min, 0.5 min, 1 min,1.5 min, 2 min, 10 min, and 30 min. HPLC analysis of the blood samplesindicated that the Tmax for triazolam was about 0.25 minutes, with aconcentration of greater than 100 ng/mL reached.

What is claimed is:
 1. A composition for delivery of a therapeuticcompound, comprising a condensation aerosol a) formed by volatilizing atherapeutic compound selected from the group consisting of alprazolam,estazolam, midazolam or triazolam under conditions effective to producea heated vapor of the compound, and condensing the heated vapor of thecompound to form condensation aerosol particles, and b) characterized byless than 5% compound degradation products, and c) aerosol MMAD is lessthan 3 μm.
 2. The composition according to claim 1, wherein thecondensation aerosol particles are characterized by less than 2.5percent by weight of alprazolnm, estazolam, midazolam or triazolamdegradation products.
 3. The composition according to claim 1, whereinthe condensation aerosol particles comprise at least 90 percent byweight of alprazolam, estazolam, midazolam or triazolam.
 4. Thecomposition according to claim 1, wherein the condensation aerosolparticles comprise at least 95 percent by weight of alprazolam,estazolam, midazolam or triazolam.
 5. A method of producing thetherapeutic compound alprazolam, estazolam, midazolam or triazolam in anaerosol form comprising: a) volatilizing a therapeutic compound selectedfrom the group consisting of alprazolam, estazolam, midazolam ortriazolam under conditions effective to produce a heated vapor of thecompound, and b) during said volatilizing, passing air through theheated vapor to produce aerosol particles of the compound comprisingless than 5% compound degradation products and c) aerosol MMAD is lessthan 3 μm.
 6. The method according to claim 5, wherein the aerosolparticles are formed at a rate of greater than 0.5 mg/sec.
 7. The methodaccording to claim 5, wherein said volatilizing includes heating acoating of the therapeutic compound, which is formed on a solid supporthaving the surface texture of a metal foil, to a temperature sufficientto volatilize the compound from the coating.
 8. The method according toclaim 5, wherein the aerosol particles comprise less than 2.5 percent byweight of alprazolam, estazolam, midazolam or triazolam degradationproducts.
 9. The method according to claim 7, wherein the coating of thecompound on said solid support surface has a thickness between 0.2 and4.8 microns.
 10. The method according to claim 5, wherein the aerosolparticles comprise at least 95 percent by weight of alprazolam,estazolam, midazolam or triazolam.